The present invention relates generally to the field of semiconductor manufacturing and more particularly to phase isolation of atomic level etching and deposition.
The use of quasi-atomic level etching (ALE) and atomic level deposition (ALD) are increasingly becoming prevalent in the semiconductor high volume manufacturing (HVM) industry. These processes involve injection of gases into a process chamber that are mutually exclusive in time domain or as a gas in phase isolation to bias. For example, in a dielectric ALE process, a polymer source such as C4F6 is injected into the chamber during phase exclusion of RF Bias. In another example, in ALD process, a precursor gas such as TiCl4 and an oxidizer such as H2O is used in the process.
There are several issues with the current ALE and ALD manufacturing process. One issue is the dead timing. For example, dead timing is delay time between switching the precursor gas to deposition gas. Shutting off any gas has two non-productive yet time-consuming steps such as the “inertia of the valves/flow controllers to shut off the gas” and “purge the gas in the process chamber before turning on the next gas or RF turn on.” Another issue is “phase isolation” which plagues atomic layer wafer manufacturing. Phase isolation occurs when there is a mixture of the precursor gas and the deposition gas in equal amount, which prohibits quality layering for deposition. Hence, phase isolation affects the throughput of the manufacturing process on a wafer basis.
Accordingly, a need is required to minimize phase isolation and dead time during the wafer manufacturing process.